This invention relates generally to diagnostic and therapeutic devices for insertion into a patient""s body, and more particularly to devices for access to and delivery of treatment in the pericardial space.
Access to the pericardial space is desirable in order to provide a variety of cardiac therapies, including delivery of drugs or genetic agents, placement of electrical leads for pacing, cardioversion, defibrillation or EGM monitoring, removal of pericardial fluid for diagnostic analysis, or other purposes. A variety of mechanisms have been developed for accessing the pericardial space, ranging from a simple puncture by means of a large bore needle to intricate catheter or cannula based systems provided with sealing and anchoring mechanisms. Access to the pericardial space may be accomplished from either outside the body, by piercing the pericardium or from inside the heart, by piercing the wall of a heart chamber.
Prior art mechanisms adapted to access the pericardial space by piercing the heart chamber include U.S. Pat. No. 5,797,870 issued to March et al, which discloses use of a transvenous catheter provided with a hollow helical needle to pierce the wall of a heart chamber. Alternatively access to the pericardial space may also be accomplished by means of a transvenous catheter which pierces the wall of a heart chamber and allows passage of a lead therethrough is disclosed in U.S. Pat. No. 4,946,457 issued to Elliot, U.S. Pat. No. 4,991,578 issued to Cohen. and U.S. Pat. No. 5,330,496 issued to Alferness. Particularly in the context of access to the pericardial space via the right atrium, it has been proposed that the transvenous catheter pierce the right atrial wall, as in U.S. Pat. No. 4,946,457 issued to Elliot or that the catheter pierce the right atrial appendage as in U.S. Pat. No. 5,269,326 issued to Verrier. Access to the pericardial space from the exterior of the body, accomplished by passing a cannula or catheter type device through the chest wall and thereafter passing the cannula or catheter through the pericardium into the pericardial space is disclosed in U.S. Pat. No. 5,827,216 issued to Igo, U.S. Pat. No. 5,336,252 issued to Cohen and, PCT Patent Application WO/99/13936, by Schmidt.
The present invention is directed toward providing a mechanism for accessing the pericardial space which provides for stable short term or long term placement of a delivery catheter or cannula having its distal most end located in the pericardial space. The catheter or cannula may be introduced into the pericardial space either transvenously through the wall of a heart chamber or transthoracically by penetrating the chest wall and the pericardium.
In particular, some embodiments of devices according to the present invention are provided with a mechanism for stabilizing the distal end of the catheter or cannula. In a first embodiment of the invention, the mechanism for stabilizing the distal portion of the catheter or cannula comprises an extensible elastic, generally tubular member located at the distal end of the catheter or cannula. The device is provided with a mechanism for extending the tubular member longitudinally, causing its diameter to diminish substantially. The tubular member is passed through the wall of the heart or the pericardium in its extended configuration and thereafter, the distal most portion of the tubular member is moved proximally, causing its diameter to enlarge, anchoring the distal end of the catheter or cannula to the pericardium or to the wall of a heart chamber. In these embodiments, the device is preferably provided with a shoulder or flange located proximal to the extendible tubular member, for location on the opposite side of the heart wall or pericardium from the distal end of the catheter or cannula.
In other embodiments of the present invention, the catheter or cannula takes the form of two nested tubular members, each provided with an extensible flange. The innermost of the two tubular members is provided with one or more radially extending protrusions or recesses, which engage with one or more corresponding protrusions or recesses located on the interior surface of the outer tubular member. Preferably, a series of outwardly directed protrusions on the inner tubular member and a series of inwardly directed protrusions the outer tubular member are provided, together defining multiple detent points for stabilizing the longitudinal position of the inner and outer tubular members relative to one another. More preferably, the protrusions and indentations of the tubular members extend around less than the entire circumference of the tubular members and are arranged so that in a first configuration, the tubular members may be slid longitudinally with respect to one another without interference between the protrusions on the inner and outer tubular members and in a second configuration the protrusions on the tubular members are interlocked to prevent relative longitudinal movement. In use, the catheter or cannula is employed by first passing the distal tip of the inner tubular member through the pericardial wall or the wall of a heart chamber such that the flange located thereon is located inside the pericardial space. The outer tubular member is then moved distally relative to the new tubular member to a point where the inner and outer flanges are located on either side of the pericardium or the heart wall, and the interlocking protrusions on the inner and outer catheter are thereafter employed to stabilize the catheter by preventing further relative longitudinal movements of the inner and outer tubular members.
In addition to the delivery of drugs, extraction of pericardial fluids, and location of medical electrical leads typically as typically accomplished by means of pericardial access to devices, the devices according to the present invention may also be employed as part of a system for accomplishing cardiac ablation. In this context, after stabilization of the catheter""s or cannula""s distal end in the pericardial space, an ablation catheter is passed through to the catheter or cannula into the pericardial space, is located at a desired location adjacent the epicardium of the heart and is thereafter employed to ablate cardiac tissue. In this context, preferred embodiments of ablation catheters for use according to the invention are provided with one or more suction ports, allowing the distal portion of the catheter to be adhered to the surface of the epicardium by suction, along with one or more electrodes, located to contact the epicardium of the heart when the distal portion of the ablation catheter is secured to the epicardium by suction.
In additional embodiments of the invention, the catheter or cannula for accessing the pericardial space takes the form of part of an implantable lead system, in which the introducer catheter or cannula is provided with one or more electrodes adapted to be located in a desired chamber or chambers of the heart, and wherein an electrode lead is passed distally through the catheter or cannula into the pericardial space, to locate additional electrodes adjacent desired portions of the epicardium of the heart. For example, electrodes located within the chamber or chambers of the heart may include pacing, cardioversion or defibrillation electrodes, and additional such electrodes may be located on the lead passing through the catheter or cannula into the pericardial space.